Explanation:
The following table summarizes the ground state electron configuration of the first 20 elements on the periodic table.
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ATOMIC STRUCTURE. 3.4 - Electron Configurations of Atoms.
Name Atomic Number Electron Configuration
Argon 18 1s2 2s22p63s23p6
Period 4
Potassium 19 1s2 2s22p63s23p64s1
Calcium 20 1s2 2s22p63s23p64s2
